Automatic weighing device.



F.,E. LAYMAN.

AUTOMATIC WEIGH ING DEVICEe APPLICATION HLED Ams, 1912.

1,260,556. Patented Mar. y26, 191s.

2 SHEETS-SHEET l.

F. E. LAYMAN.

AUTOMATIC WEIGHINGIDEVICE,

APPLICATION FILEDAPR-8. |912.

1,260,556. Patented Mams, 1918.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OEEICE.

FRANK E LAyuAN, or MILWAUKEE, WISCONSIN, AssIGNon To THE Corina-HAMMER MFG. CO.,.OI` MILWAUKEE, WISCONSIN, A CORPORATION or WISCONSIN.

`AUTOMATIC WEIGHING DEVICE.

Specieation of Letters Patent. Patented Mar. l26, 1918. l

Application led April 8, 1912. Serial No. 689,244.

v.which is compact in form. Another object is `to provide a weighing machine which gives very accurate results even when small amounts of material are weighed. A further' object is to provide a weighing machine having means for feeding material onto the scale pan at a more uniform rate than here- 'l tofore. An additional object is to provide a weighing machine in which there is an accelerated positive downward movement of the. scale pan as soon as the weightof the material thereon overbalances the lcounterweight, thereby eliminating the oscillations of the scale beam and increasing the rapidity of the weighingy operation. Other objects will be apparent from the more detailed description hereinafter given.

In the accompanying drawings I have illustrated a construction which embodies my invention. Other forms may, of course, be devised.V i Y In the drawngsz- Figure 1 is a side elevation of the preferred construction.

Fig. 2 is an end elevation thereofpartly insection.

Fig. 3 is .an elevation ofthe side opposite conveyer 4. This conveyer and the scraper or agitator 5, which provides for a uniform feeding of the material to the conveyer, are driven preferably by an electric motor 6, although I donot limit myself to electrical driving means, as a Suitable mechanical drive may, of course, be employed. I prefer to use an electric motor, however, as various auxiliary electrical devices may be conveniently operated from the .,motor circuit as hereinafter described.

The screw conveyer 4 is mounted so as to rotate in a suitable cylindrical chamber 7 and is driven by the` motor through intermediate connections ywhich include the worm and gear '8, 9 and the skew gears 10, 11. See Figs. 3 and 4. These gears and the additional skew gear 12, are suitably mounted in a casing or compartment 13 on the side of the supportin frame 1. The agitator or scrapery 5 is a so driven by the motor through the' same gears just described, and through theadditional worm and gear 14, 15 ,and beveled gears 16, 17.

The hopperis provided with a suitable sliding cover -18fto provide for the introduction of the material to be weighed. The scraper 5, which rotates in close proximity to the conical lower wall of the hopper, provides for a uniform feeding of the material to the screw conveyer. The screw conveyer advances` the material to the outlet 19, the lower end of which is normally open but may be closed by a suitable shutter 20 pivoted at 21 and having an arm 22 connected to a suitable spring 23 in such a manner that the opening and closing of the shutter causes said arm to snap back and forth 'over a dead center, thereby providing f for a quick closing of the outlet 19.

The opening and closing of said shutter is effected by a solenoid 24 which, when energized or denergized, draws up or releases its plunger 25, thereby imparting a throw to the bell crank lever 26 which moves up or down and causes the shutter 2O to snap open or shut. The connections between the plunger. 25 and the bell crank lever 26 include an .additional bell crank lever 27 and a link 28, the operation of which will be apparent from an inspection of Figs. 1 and 4. The plunger 25 is also provided with a Contact member 29 which bridges the stationary contacts 30 when in uppermost position, thereby closing the motor circuit, and which also opens the motor circuit with an abrupt movement when the circuit to the solenoid is opened automatically by the weighing scale 4ashereinafter described.

The weighing scale, as previously stated, is preferably constructed entirely independent mechanically, of the rest of the apparatus, although I do not limit myself to said independent construction. It comprises preferably the usual elements of a scale, includinp,` a scale beam 31 suitably pivoted at the point 32 and carrying at one end the Scale pan 33 and at the other end the adjustable counterweight 34. In addition to the usual elements, however, it is provided with an automatic locking device comprising a catch 35 which engages a coperating catch on the end of a bell rank lever 36. The bell crank lever is normally held with one end resting on a rotatable cam or block 37 by the spring 38. It is apparent that when the weight of the material in the scale pan causes the saine to overbalance the counterweight, said scale pan as it lowers will be locked in lower position by the spring catch. By rotating the cam 37, however, the scale pan may be readily released and raised. When the scale pan is in uppermost position or in balanced position the circuit to the solenoid 24.- is closed through a suitable switch contact 38 carried on a suitable insulating base 39 which is mounted on the base of the Weighin scale 3. An adjustable bail 40 is secure to the scale beam 31 such a manner as to lift the contact end of the switch contact 38 as soon as the material in the scale pan overbalances the counterweight 34, thereby instantly opening the circuit to the solenoid 24 and simultaneously opening the motor circuit at the contacts 29, 30. Accordingly, the feeding of the material from the hopper ceases instantly Awhen the redetermined weight of material has been eposited on the scale pan and simultaneously the lower end of the outlet 19 is closed by the shutter 20.

It should be noted that the shutter 20 is located at the lower end of the outlet 19. Accordin ly, the material falling through the main y portion of the outlet 19 is instantly arrested as soon as the desired weight of material has'accumulated on the, scale pan. Accordingly, the only excess material which reaches the scale pan after the circuit is opened by the contact 38, is the material which at the. time is actually falling throughthe short distance -from the lower end of the outlet 19 to the scale pan.

This amount is very small and is quite constant in view of the uniform rate at which the material is being fed from the hopper, so that the error involved is quite small. By

virtue of this arrangement a properly oonstructed scale is capable of weighing uniormly within a small fraction of a gram when weighing only a few grams.

When the scale is in balanced position the material on the scale pan and the adjustable counterweight areboth above the point 32 Where the scale beam is pivotally supported. Accordingly, it will be apparent that as soon as lthe material in the scale pan overbalances the counterweight, the scale pan will begin to lower, the downward movement thereof being along the arc of a circle, which is, however, a substantially vertical path. The upward movement of the counterweight is also along the arc of a circle which constitutes, however, an inclined path. The lever arm or the distance measured from Vthe pivot 32 to a vertical line drawn through said counterweight, decreases as the counterweight is raised. Accordingly, the turning moment of the counterweight4 decreases as it is raised. The turning moment produced by the material in the scale pan, moreover increases as the same descends. As a result the overbalancing effect of the scale pan increases as the pan lowers, giving a positive and accelerated downward movement thereto 'which insures a quick, positive opening of the circuit by the contact arm 38 and which insures also the interlocking of the spring catch elements. The advantages of the above described positive movement are, first, freedom from oscillation or vibration of the scale beam 31 after the scale has reached anbalance, and, second, an increased rapidity in the weighing operation. Without the'above arrangement the scale beam ing and closing the circuit at the switch member 38 and causing a chattering-of the solenoid contact 29, which would subject the motor to a very objectionable series of sudden starts and stops and which would also cause the deposit of additional material on the scale pan. y

It is to be understood, of course, that the above apparatus as a whole, and the various arran ents and combinations of elements in uded therein, have been selected for the purpose of illustration only. Various other devices may be constructed which embody the features of the invention. Accordingly, I do not desire to limit myself to the construction described exce t where limitations are imposed in the claims, but I desire to cover broadly suitable equivalent means for accomplishing the desired results wherever said means fall within the scope of said claims.

What I claim as new and desire to Secure by Letters -Patentof the United States is 1. A weighing scale comprising a scale b eam, a scale pan and a counterweight carried thereby at a substantial elevation above the pivot thereof for providing v' lll accelerated downward movement of said scale pan when the scale overbalances, a circuit contact, and a lost motion connection between said beam and said contact for insuring actuation of the latter to open a eircuit on'ly upon accelerated movement of the former. y

2. A weighing scale comprising a scale beamv` a scale pan and a counter-weight carried thereby at a substantial elevation above the pivot thereof whereby an accelerated downward movement is imparted to said scale pan when the scale overbalances, a. switch operating member having an adjustable lost motion` connection with said scale beam for actuation thereby to abruptly open a circuit during only the accelerated movement of said beam."

3. A weighing scale comprising a scale beam` a scale pan and a counterweight carried thereby and arranged to insure an accelerated movement of said scale beam following overbalance of said scale, a pivoted switch operating member` having an adjustable lost motion connection with said scale beam for abrupt actuation thereby during only the accelerated movement thereof to vary an electric circuit.

4. In an automatic weighing machine, a receptacle for `the material to be weighed, a weighing scale, a screw conveyer associated with said receptacle for advancing said material toward the scale pan, a scraper for feeding said material uniformly to said.

conveyer, a discharged tube through which said material passes from said conveyer to said scale pan, a valve located in the lower end of said discharge tube, a motor for op- -erating said scraper and said conveyer, and

a relay controlling the motor circuit and actuating said valve, the circuit of said relay being normally closed by a contact member 'actuated by a predetermined movement of pan, means for increasing the relative value i of the turning moment of said scale pan with respect to said counter-weight when the scale overbalances whereby an accelerated movement is imparted to said scale beam, thereby opening said circuit with a quick positive movement of the switch contact, and a spring latch for preventing a return movement of said switch contact.

6. In an automatic weighing machine, in combination, a material container, a receiving and weighing scale, a conveying chute therebetween having a power-feed portion adjacent said container and a gravity feed extremit adjacent said scale, power operated fee ing means for conveying the material from said container to said extremity of said chute, a valve arranged in said extremity, means for stopping said feedin means and closing said valve when sai scale responds to a predetermined weight thereon, and means for ei'ecting the closure of said valve with a snap action.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

' FRANK E. LAYMAN.

Witnesses:

FRANK H. HUBBABD, H. L.- Rocxwnu.. 

